Milo g-



(No Model.)

M. G. KELLOGG.

MULTIPLE SWITGHBOARD.

No. 592,395. Patented Oct. 26,1897.

UNITED STATES PATENT FFICE;

MILO G. KELLOGG, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE KELLOGG S\VITOHBOARD AND SUPPLY COMPANY, OF SAME PLACE.

MULTIPLE SWITCHBOARD.

- SPECIFICATION forming part of Letters Patent No. 592,395, dated October 26, 1897.

Application filed May 1o 1891. Serial No. 392,964. (No model.)

To ctZZ whom it may concern:

Be it known that I, MILO G. KELLOGG, of Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Multiple Switchboards for Telephone-Exchanges, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to a telephone-exchange system in which the lines are metallic-circuit lines and in which the necessary switching between the lines is accomplished by means of pairs of double or loop plugs connected together by double flexible cord conductors.

It consists first, of a system of testing the lines at any board to determine whether or not they are in use; secondly, of an organization of loop-switches and connections for said cords by which the movements required of the operator in making the necessary connections and diseonnections are few and convenient to make, and, thirdly,.of an arrangement of the annunciators and switches of the different lines by which special clearing-out annunciators are not required.

In the accompanying drawings, illustrating my invention, Figure 1 represents sectional views of sections of two multiple switchboards and the main-line central-office connections and apparatus of the two lines connected to the two switchboards. Fig. 2 represents a diagram of an operators cord system and apparatus necessary to illustrate my invention. Fig. 3 represents an operators test system.

I place as many switchboards in the central olfice as are found necessary or desirable in order to properly operate the exchange. On each board is a spring-jack switch for each line. Each switch has a contact-spring which normally connects with a contact-point and is separated from the point while a plug is inserted into the switch and has a contactpiece insulated from the rest except by the circuit connections. To the contact-point is attached an extension-piece or connection along the surface of the switch-hole by means of which one of the contact-pieces of the loop test-plug (hereinafter described) forms connection with the contact-point when the plug is inserted, as hereinafter described. The insulated contact-piece mentioned above is also placed along the surface of the switchhole and preferably in front of said extensionpiece to the eontact-point and is soplaced that one of the eontact-picces of the loopswitch plugs (hereinafter described) forms connection with said contact-piece when the plug is inserted. Said plugs are so constructed and said contact-pieces and extension-pieces of the switches are so placed that when the test-plug is inserted into a switch the contact-piece of the plug does not come into contact with said contact piece and when a switch-plug is inserted into a switch the contact-piece of the plug does not come into contact with the extension-piece or point of the switch.

In Fig. 1, A A are sectional views of sections of the two switchboards shown. 9 9 represent the springs of the different switches, h h the contact-points of the switches on which the springs normally rest, and h h the extension-pieces of the points placed along the surface of the holes of the switches in front of the points. j j are the insulated contact-pieces of the switches, also placed along the holes of their respective switches and preferably in front of the extensionpieces. a Z) are rubber strips on which the metal parts of the switches are mounted and through the fronts of which are the switchholes ZZ. These holes are rectilinear holes and are adapted to receive the loop-plugs mentioned above and to cause them to operate the switches, as described. W and X are calling-annunciators, one for each line shown and each connected into the circuit of its line, as will hereinafter be described. B B are test-batteries, one for each line and each connected into the circuit of the line, as will hereinafter be described. Two metallic-circuit lines are shown in the figure, and they are connected to their respective boards as follows and as shown: One side or branch of the line is connected to the contact-pieces jj of its switches on the several boards. The other side or branch of the line passes successively through pairs of contacts g h of its switches in the circuit between the last pair of contact-f points before the two branches are united and the pair of points immediately preceding the said last pair of contact-points.

,last pair and is located at the same board as I The two branches of the line are normally on closed circuit at the subscribers station and may be provided with any usual and appropriate subscribers-station apparatus.

In the operators cord system shown in Fig. 2,

D D are a pair of loop-switch plugs adapted for use with the switches shown in Fig. 1. r r are the rubber insulations of the plugs. S S are the two contact-pieces of the plug. The-plugs are constructed and the contactpieces are arranged so that when a plug is inserted into a switch the spring is pressed away from. its contact-point, the contactpiece S forms connection with the spring g, the contact-piece S forms connection with the contact-piece j of the switch, and the contact-point h is insulated from the contactpieces of the plug. The plugs should be inserted into the switches in such a direction that they form the connection as above described.

Yis the looping-in switch for the pair of cords shown. and B is her calling-generator. The loopingi-n switch has two levers and three pairs of contact-points, on which the levers may be alternately placed at the will of the operator. One pair of the contact-points are marked m m, and they are connected by a loop which contains the operators telephone. The pair adjoining them are marked an, and they are connected by a loop which contains the opermoves with the lever.

ators calling-generator. The next pair are marked 19 p, and they are connected by a simple loop. When the levers pass from m m to 13 13, they rest on n n.

Onecontact-piece of one plug of the pair of plugs is connected by flexible conductor to one contact-piece of the other plug. The two other contact-pieces of the plugs are connected by flexible conductors to the two levers of the switch.

00 are a pair of contact-points, of which 0 is a stationary point and is connected bya circuit-wire to the cord-circuit which conneots the two contact-pieces of the plugs which are-not directly connected to the switchlevers, and 0 is a contact-point which isconnected to one of the levers, as shown, and The contact-points 0 0 are in contact when the switch-levers are on the contact-points m m and are out of contact when the levers are moved to the other points of the switch.

'Onlyone pair of switch-plugs with their 25 is the operators telephone,

at her board for her work.

cords and looping-in switch are shown. Other pairs as are found desirable may be added to the operators system in a way which will be apparent to those skilled in the art. She needs but one telephone and calling-generator.

The levers of each looping-in switch nor- 'mally rest on the contact-points m m.

In the operators test system shown in Fig. 3, T is the loop test-plug, and t is the test receiving instrument, which may be the operators telephone or any suitable instrument. u is the rubber insulation of the plug, and o 'u are its contact-pieces. structed and the pieces are arranged so that when the plug is inserted into any switch the spring is pressed away from the contact-point, the contact-piece 1; forms connection with the spring g, the contact-piece 12 forms connection with the extension-piece h, and the contact-piecej of the switch is not in contact with the contact-pieces of the plug. The plug should be inserted into the switches in such a direction that they form the connections as above described. The two contactpieces 12 o of the plug are connected by a flexible conducting-loop, in which is the test receiving instrument.

Each operator has a cord system and a test system, and they are conveniently mounted The conductingcords of the plugs should be long enough so The plug is con-' that she can connect any plug with any switch at her board. 7

The operation of the switch system is as follows: When an operator receives a call on the annunciator of a line, she places the plug D of a pair of her plugs in the switch of the line. By so doing she opens the closed circuit of the line and loops her telephone into the circuit. The closed circuit of the line is opened at the pair of contacts g h of the switch. The two cords of the plug are connected to the two branches of the line by the connection of the two contact-pieces of the plug with the two contact-pieces g and j of the switch, and the two cords are bridged or connected by the contacts 0 0 of the looping-in switch. When the operator finds out by conversation what line is wanted, she tests the line wanted, as will be hereinafter described, and if she finds it is not. busy she places the plug D of the pair in the switch of the line, opening the closed circuit of the line and connecting its two branches to the cord-circuits of the plug. She then moves the levers of the looping-in switch so that they rest on the points n n. By so doing the bridge connection between the cords at o 0 is removed and a signal-current from the operators generator goes to the metallic circuit. She then moves the levers of the switch so that they rest on p p, and the lines are connected in metallic circuit for conversation with neither the operators telephone n01 generator in the circuit. When the operator receives the .in its line-switch at any board, the test-battery of the line is in a cut-off portion of the line-circuit and is then in open circuit. This is readily seen from the fact that the contact h of the switch in which the switch-plug is placed, which contact is connected to one side of the battery, is opened or disconnected from the contact g of the switch, while the two contacts of the plug are then in contact with the contact 9 of the switch and with contact h of the switch, respectively, which latter contact is connected to theline-circuit on the other side of the test-battery. Thus the testbattery is then switched from circuit with the line and is in an open cut-off portion of the circuit.

The test system is as follows: When an operator at any board tests any line, she places her test-plug in the switch of the line and by so doing connects the two contact-pieces of the plug with the two contact-points g h of the switch. If the line is not switched at any board, the test receiving instrument will be included in the close metallic circuit of the line and the test-battery of the line,and the instrument will sound, indicating that the line is free to be connected to. If, however, when the test is made the line is switched at some board and the plug is inserted in the cut-off portion of the line, the circuit of the test receiving instrument is open at the contactpoints 9 h of the switch used in switching, and the instrument will not sound. If, again, when the line is switchedthe test-plug is inserted in the portion of the circuit which is included with the other line, the instrument will not sound, because the test-battery is not included in the circuit with it, being then, as stated above,in the cut-01ft portion of the line. Therefore in either case whenever a line is switched for conversation at any board and a test-plu g is inserted into the switch of the line at any other board no closed circuit is established which contains a test receiving instrument and battery, and the test receiving instrument cannot then respond, because no current is passing through it. WVhen, therefore, the test is made and the instrument does not sound, the operator knows that the line is switched at some board.

- lVhen a call is received on a line and it is answered and the line is connected, as described, with another line whose calling-an: nunciator is located at another board, the a11- nunciator of the line in which the call originated is in their circuit and the annunciator of the other line is not included in the circuit. As the annunciator which is in the circuit is located at the board where the connection is made, any clearing-out signal sent over the circuit will be received and can be attended to at the board where the connection is made. This system therefore provides for a clearing-out annunciator in the circuit of any two lines connected together without requiring a special clearingout annunciator for each pair of cords.

When in this system the line is not switched for conversation and the subscriber who has sent in a call on his annunciator has removed his telephone from its switch to listen for the operator to answer his call, bat tery-current of constant character is passing through his telephone. On account of the character of the current, however, no sound or noise will be produced in his telephone. lVhen, however, the operator at the central office places a switch-plug into the switch of the line to answer the call, the battery-current through the subscribers telephone will be automatically broken or interrupted, and the subscriber will consequently hear a click or sound in his telephone. He will thereby know that the operator has connected his telephone with his line and can at once proceed to talk and give his order to the operator without waiting for the latter to inform him by word that he is ready to receive the order.

I claim as my invention- 1. In a telephone exchange system, multiple switchboards, metallic-circuit lines and switches for said lines, one for each line on each board, each switch having a pair of contacts normally closed through which in series one side of its line passes to one side of an individual test-battery for the line, each switch having a third or insulated contact to which the other side of the line and the other side of the individual test-battery for the line are connected, and said individual test-batteries, one for each line, in combination with switching apparatus at each board connecting the two sides of any line with another line by opening the normally closed pairs of switch-contacts of the line at the board and forming connection with one of said normally closed contacts and said third or insulated contacts respectively, and test receiving outfits, one at each board, each having a test receiving instrument and a loop testplug to the two contacts of which plug the two sides of the test receiving instrument are respectively connected, each looptest-plug being adapted to be inserted into each switch at its board, and when inserted opening the pair of normally closed contacts, and forming connection between the two contacts of the plug and said two normally closed contacts of the switch respectively.

2. In a telephone-exchange system,m ultiple switchboards, metallic-circuit lines, switches for said lines, one switch for each line on each board, one side or branch of each line passing successively through pairs of contacts of the line-switches on the several boards and from the last contact-point through a testbattery to contact-pieces, one for each switch IIO the contact-pieces of the switch-plug with, that contact-point which is connected with said first-mentioned side or branchof the line, while the other contact-pieceof the plug forms connection with said contact-piece of the switch and test receiving instruments, oneat each board, each connected on its two sides 1 to the two contact-pieces of a loop test-plug adapted to be inserted into any switch at its board and when inserted to disconnect the pair of contact-points of the switch and form connection between them and its two contact-pieces, substantially as set forth.

3. In a telephone-exchange system, a pair of loop-switch plugs the two contact-pieces of one of which are connected to the two contact-pieces of the other, respectively, by two flexible switch cord conductors in combination with a switching device having a movable lever or commutator piece and two contacts operated by said commutator-piece to be opened and closed to each other, one contact being connected to one of said flexible switch cord conductors and the other contact to the other of said flexible switch cord conductors, by which the operator may at will connect or disconnect said cord conductors, substantially as set forth.

4. Ina telephone-exchange system, a pair of loop-switch plugs, the two contact-pieces of one of which are connected to the two contact-pieces of the other, respectively, by two flexible switch cord conductors, in combination with a switching device, having a movable part containing two levers connected in series in one of said cord-circuits connected to the two plug contact-pieces respectively of that cord-circuit, a pair of contacts connected through the operators telephone with which said levers in one position connect, another pair of contacts in electrical connection with which said levers in another position connect, and a pair of contacts connected tothe two cord-circuits respectively closed to each other when the levers are in the first-' mentioned position and open to each other when the levers are in the second-mentioned position, by which when the movable part of the switch is in one position the two cordcircuits are connected together and the telephone is in one of the cord-circuits and when the movable part is in another position said connection between the cord-circuits is open and the telephone is switched from'the cordcircnit, substantially as set forth.

5. In a telephone-exchange system, a pair of loop-switch plugs the two contact-pieces of one of which are connected to the two contact-pieces of the other, respectively, by two flexible-cord circuits, in combination with a switching device, having two. levers in one of said cord-circuits connected to the two plug contact-pieces respectively of that cord-circuit, a pair of cont-acts connected through the operators telephone with which said levers in one position connect another pair of contacts connected through a calling-generator with which said levers in another position connect, and a pair of contacts connected to the two cord-circuits respectively closed to each other when the levers are in the first-mentioned position and open to each other when the levers are in the second-mentioned position, by which when the movable part of the switch is in one position the two cord-circuits are connected together and the telephone is in one of the cord-circuits and when it is moved to another position said .connection between the cord-circuits is open,the telephone is switched from the cord-circuit and the calling-generator is included in the same cord-circuit, substantially as set forth.

6. In a telephone-exchange system, a pair of loop-switch plugs the two contact-pieces of one of which are connected to the two contact-pieces of the other, respectively, by two flexible-cord circuits, in combination with a .switchingdevice having two levers in one of said cord-circuits connected to the two plug contact-pieces respectively-of that cord-circuit, a pair of contacts connected through the operators telephone with which said levers in one position connect another pair of contacts connected through a calling-generator with which the levers in another position connect, another pair of contactsin electrical connection with which said levers in another position connect, and a pair of contacts connected to the two cord-circuits respectively closed to each other when the levers are in the firstmentioned position and open to each other when the levers are in the second-mentioned position, by which when the movable part of the switch is in one position the two cord-circuits are connected together and the telephone is in one of the cord-circuits, when the movable part is placed in another position the telephone is switched from the cord-circuit, the cord-circuits are disconnected and the calling-generator is included in one of the cord-circuits and when the movable part is placed in another position, the cord-circuits are disconnected from each other and from both telephone and generator, substantially as set forth.

7. In a telephone-exchange system, a pair of loop-switch plugs the two contact-pieces of one of which are connected to the two contact-pieces of theother, respectively, by two flexible-cord circuits, in combination with a switching device having two levers in one of said cord-circuits connected to the two plug contact-pieces respectively of that cord-circuit, a pair of contacts connected through the operators telephone with which said levers in one position connect another pair of con,

tacts connected through a calling-generator with which the levers in their next position connect another pair of contacts in electrical connection with which said levers in another position connect, and a pair of contacts connected to the two cord-circuits respectively closed to each other when the levers are in the first-mentioned position and open to each other when the levers are in the second-mentioned position, by which when the movable part of the switch is in one position the two cord-circuits are connected together and the telephone is in one cord-circuit; when the movable part is in the adjoining position said connection between the cord-circuits is open and the telephone is switched out of and the generator is switched into one of the cord-circuits; and when the movable part is in its third position said connection betweenthe cord-circuits is open and they are disconnected from both telephone and generator, substantially as set forth.

8. In a telephone-exchange system, a pair of loop-switch plugs the two contact-pieces of one of which are connected to the two contact-pieces of the other respectively, by two flexible-cord circuits, in combination with a switching device having two levers in one of said cord-circuits connected to the two plug contact-pieces respectively of that cord'circuit, a pair of contacts connected through the operators telephone with which said levers in one position connect another pair of contacts connected through a calling-generator with which the levers in their next position connect another pair of contacts in electrical connection with which said lines in another position connect said levers being adapted by one motion to be placed successively on said pairs of contacts, and a pair of contacts connected to the two cord-circuits respectively closed to each other when the levers are in the first-mentioned position and open to each other when the levers are in the second-mentioned position, whereby by one motion or operation the operator may first disconnect the two cord-circuits and switch the telephone out of one of them, secondly switch the generator into one of them and thirdly switch the generator out of the circuit, substantially as set forth.

9. In atelephone-exchange system, two metallic-circuit telephone-lines temporarily connected together in metallic circuit for conversation, in combination with a switching device having two levers in one of said cordcircuits connected to the two plug contactpieces respectively of that cord-circuit, a pair of contacts connected through the operators telephone with which said levers in one position connect, another pair of contactsin electrical connection with which said lines in another position connect, and a pair of contacts connected to the two cord-circuits respectively closed to each other when the levers are in the first-mentioned position and open to each other when the levers are in the second-mentioned position, by which the operator can at will switch the telephone into the metallic circuit and at the same time bridge or orossconnect the two sides of the metallic circuit, substantially as set forth.

10. In a telephone-exchange system, two metallic-circuit lines temporarily connected together for conversation, in combination with a switching device having two levers connected respectively to the two terminals of one sideor branch of said circuit, a pair of contacts connected through the operators telephone, with which said levers in one position connect another pair of contacts connected through a calling-generator with which said levers in another position connect, and a pair of contacts connected to the two sides respectively of said metallic circuit closed to each other when the levers are in the first mentioned position and open to each other when the levers are in the second-mentioned position, by which the operator may at will open such bridge or cross connection and switch the telephone out of and the generator into the circuit, substantially as set forth.

11. In a telephone-exchange system,two metallic-circuit lines temporarily connected together into metallic circuit for conversation, in combination with a switching device having two levers connected respectively to the two terminals of one side or branch of said circuit, a pair of contacts connected through the operators telephone with which said 1evers in one position connect another pair of contacts connected through a calling-generator with which the levers in another position connect, another pair of contacts in electrical connection with which said levers in another position connect, and apair of contacts connected to the two sides respectively of said metallic circuit closed to each other when the levers are in the first-mentioned position and open to each other when the levers are in the second-mentioned position, by which the operator may at will open such bridge or cross connection and switch the telephone out of and the generator into the metallic circuit or leave the circuit unconnected with either telephone or generator, substantially as set forth.

In testimony whereof I have hereunto subscribed my name.

MILO G. KELLOGG. WVitnesses:

FRANK S. Onnn, EDWARD C. DAVIDSON. 

